Image forming apparatus including control circuitry to execute a warm-up operation

Abstract

An image forming apparatus includes a developing device including at least one stirring rotator configured to stir a developer in the developing device, a driver configured to drive the at least one stirring rotator in forward and reverse rotation, a device detector configured to detect whether the developing device is set in the image forming apparatus, and control circuitry configured to execute a warm-up operation. In the warm-up operation, the driver drives the at least one stirring rotator alternately in the reverse rotation and the forward rotation in response to a detection of setting of the developing device in the image forming apparatus by the device detector and a detection of a predetermined condition.

What is claimed is: 
     
       1. An image forming apparatus comprising:
 a developing device including a first stirring rotator and a second stirring rotator each to stir a developer in the developing device, the first stirring rotator being disposed in the developing device such that when the developing device is installed within the image forming apparatus, the first stirring rotator is lower with respect to a direction of gravity than the second rotator, the first stirring rotator disposed in a first transport path, and the second stirring rotator being disposed in a second transport path, the first transport path and the second transport path being connected by a communication opening through which the developer is raised from the first stirring rotator to the second stirring rotator; 
 a driver configured to drive the first stirring rotator and the second stirring rotator in forward and reverse rotation; 
 a device detector configured to detect whether the developing device is installed in the image forming apparatus; and 
 control circuitry configured to execute a warm-up operation in which the driver drives the first stirring rotator and the second stirring rotator alternately in the reverse rotation and the forward rotation in response to a detection of setting of the developing device in the image forming apparatus by the device detector and a detection of a predetermined condition, 
 wherein the driver is configured to drive the first stirring rotator and the second stirring rotator in an order of the reverse rotation and the forward rotation alternately in the warm-up operation, 
 wherein the forward rotation is a direction used to accumulate the developer for use by the developing device, and the reverse rotation transports the developer in a direction opposite to the direction used to accumulate, 
 wherein a cycle includes driving the first stirring rotator and the second stirring rotator first in the reverse direction followed by a forward rotation of the first stirring rotator and the second stirring rotator, 
 wherein the control circuitry is configured to cause the driver to drive the first stirring rotator and the second stirring rotator in the reverse rotation longer than in the forward rotation for a plurality of the cycles consecutively during the warm-up operation. 
 
     
     
       2. The image forming apparatus according to  claim 1 ,
 wherein the predetermined condition is that the developing device is unused and set in the image forming apparatus for the first time. 
 
     
     
       3. The image forming apparatus according to  claim 1 , further comprising a torque detector configured to detect torque applied when the first stirring rotator and the second stirring rotator rotate,
 wherein the predetermined condition is that the torque detected by the torque detector exceeds a predetermined threshold value. 
 
     
     
       4. The image forming apparatus according to  claim 1 , further comprising a torque detector configured to detect torque applied when the first stirring rotator and the second stirring rotator rotates,
 wherein the control circuitry is configured to increase a duration of the warm-up operation as torque detected by the torque detector increases. 
 
     
     
       5. The image forming apparatus according to  claim 1 , further comprising an image bearer,
 wherein the developing device includes a developing roller opposed to the image bearer or in contact with the image bearer, and 
 wherein the driver is configured to drive the developing roller along with the first stirring rotator and the second stirring rotator. 
 
     
     
       6. The image forming apparatus according to  claim 1 , wherein:
 the first stirring rotator and the second stirring rotator are coupled to the driver such that the first stirring rotator rotates in a direction opposite to a direction of rotation of the second stirring rotator. 
 
     
     
       7. The image forming apparatus according to  claim 1 , further comprising:
 a first gear on an end of the first stirring rotator; and 
 a second gear on an end of the second stirring rotator, the first gear and the second gear meshing such that the first gear rotates in a direction which is opposite to a direction that the first gear rotates. 
 
     
     
       8. An image forming apparatus comprising:
 a developing device including at least one stirring rotator configured to stir a developer in the developing device; 
 a driver configured to drive the at least one stirring rotator in forward and reverse rotation; 
 a device detector configured to detect whether the developing device is set in the image forming apparatus; 
 control circuitry configured to execute a warm-up operation in which the driver drives the at least one stirring rotator alternately in the reverse rotation and the forward rotation in response to a detection of setting of the developing device in the image forming apparatus by the device detector and a detection of a predetermined condition; 
 a plurality of developing devices including the developing device; and 
 a first driver and a second driver serving as the driver, 
 wherein the first driver is configured to drive the at least one stirring rotator of some of the plurality of developing devices, and the second driver is configured to drive the at least one stirring rotator of other of the plurality of developing devices, 
 wherein the number of the other of the plurality of developing devices is less than the number of the some of the plurality of developing devices, and 
 wherein an execution time of the warm-up operation with the first driver is longer than an execution time of the warm-up operation with the second driver.